The effect would be similar to when OneNote is docked to the side of the desktop, except that only a certain tabbed area (rather than the entire side of the desktop) would activate.

Or, to put it another way, it would work kind of like a regular dock, except that the dock items would be little tabs, attached to any screen edge, that I would click on, and the tab would stay attached to the window so it would shrink back when I clicked on it again. (Alternately, a tabbed application could be made to "auto-hide")